What is an Articulated Robot? | 5+ Important Applications | SCARA

Articulated Robot

Image Credits: KUKA Roboter GmbH, Bachmann, KUKA robot for flat glass handling, marked as public domain

The subject of discussion: Articulated Robot and its features

Articulated Robot | Articulated Robot Arm

Articulated Robot Definition

In industrial settings, articulated robots are the most common robot type. Robot arm with rotary joints is known as articulated robot arm. In the robotics universe, these joints are referred to as axes. These robots are typically driven by servo motors and can be as essential as a two-axis configuration or as complex as ten or more axes. Four to six axes are common in industrial robotics, with six axes being the most common.

To put it another way, this type of robot has rotary joints (e.g., a legged robot or an industrial robot). Simple two-jointed structures to devices of ten or more communicating joints and materials are examples of articulated robots. Electric motors are one of the many sources of electricity for them. Below is an example of an articulated robotic arm.

articulated robot
Articulated Robot Arm; Image Source: KUKA Roboter GmbH, Bachmann, Robotics Cutting Bridge Building Parts

Who invented the Articulated Robot?

Victor Scheinman, a Stanford University professor, invented the Stanford arm in 1969. This was a 6-axis articulated robot that was powered entirely by electricity. Thanks to this new technology, manufacturers will now use robotics for assembly and welding activities. He later sold his ideas to Unimation, which worked with General Motors to build them.

Articulated Robot Design | Articulated Robot Configuration

The robot’s joints are referred to as axes, and each axis has an extra degree of independence, referring to the robot’s individual movements. The axes are usually connected in a chain to allow each one to support a robot structure farther down the line.

Vertically Articulated Robot

The robot’s construction begins with a vertically oriented foundation that houses the first joint, hence the other name Vertically Articulated Robot. This first revolute joint connects the main robot body to the floor. Other revolute joint attaches the shoulder to the robot body and runs vertical to it and one parallel revolute joint is located at the end of the robot shoulder, that connects the shoulder to the robot’s arm.

At the end of the arm, other joints are utilized to connect the robot’s wrist to end-effector. Like the FANUC M-10ia, this robotic structure is built to resemble a human arm closely. The servo motors on the robot control each axis’ rotation, allowing for precision and speed. This has more degrees of freedom than any other kind of robot, which is why they are so popular with manufacturers and their increased range of motion closely resembles that of a human, making them suitable for assembly lines.

They also allow for more versatility in the manufacturing process. Because of their ability to make several motions, they are more adaptable to improvements in the manufacturing environment or workpieces. Enhanced movement gives the robot a more extensive work envelope, enabling it to handle a broader range of workpieces from small to massive.

How do Articulated Robots work?

The most commonly used 6-axis articulated robots can travel to any point within the operating envelope in an articulated and interpolated manner.

Articulated Robot Arm Control System

A kinematic problem resulting from the arm configuration’s nonlinearity is one of the most significant challenges in operating an articulated-robotic arm. To put it another way, the nonlinearity between the state of the robot hand (i.e., its location and orientation) and the joints’ state (i.e., their rotational angles) makes coordinate transformations more difficult. Because of this nonlinearity, there are a few singular points in the state space of joints where the robot hand’s degree of freedom is diminished and this further adds to the problem’s complexity.

Redundancy, it has been said, will successfully solve the issue of singularity while still increasing the robot’s stability and functionality.

The robot arm’s trajectory control can be understood from the Robot Kinematics section and the discussed approach can be applied for any conventional robot arm design.

Articulated Robot Workspace | Work Envelope of Articulated Robot

Any industrial robot’s function envelope is an important consideration when determining its utility. One of the main benefits of the said robot arm is that they can use the bulk of their work envelope and the only part of the envelope they cannot use is the back, which houses the cables.

On the other hand, some current architectures have internally routed power and data cables, which solves this issue and allows the robot arm to use the whole field of reach. Even the most simplistic articulated robot will optimize the available space with its footprint on the factory floor, regardless of how the cables are routed. This is a massive benefit for factories that need to think about things like output flow, protection, and floor space.

Articulated Robot Examples

5 Axis Articulated Robot

FӦRSTER 5 Axis Robot Arm; Image Source: Direct Industry

6 Axis Articulated Robot

FANUC 6-Axis Robot Arm; Image Source: PhasmatisnoxFANUC welding robot reachingCC BY 3.0

What Articulated Robots used for? | Articulated Robot Applications

These robots offer flexibility due to the wide range of tasks they can do. Arc welding, material processing, assembling, component transition, pick and place, packing, system filling, and palletizing are only a few of the applications available. Many robots such as the FANUC R-2000ib/125L, can do a variety of tasks.

Robot Arm Palletizing Bread; Image Source: KUKA Roboter GmbH, Bachmann, Factory Automation Robotics Palettizing Bread

Many robotic companies, the most well-known of which are FANUC, Yaskawa Motoman, ABB, and KUKA and majority of these companies’ robots are articulated, and popular versions include the ABB IRB 2600 and the Motoman HP20. FANUC is better known for its powerful six-axis articulated robots, such as the R-2000iA line, which have helped the company remain on top of the robotics community.

Even as new robot forms have been introduced due to technological advancements, these robots have retained their place in the automotive environment by improving production processes.

Typical uses for 6-axis articulated robots in plastic molding automation include:

  • Automated picking and handling of parts.
  • Automated in-mold decorating (IMD) and in-mold marking (IML).
  • Automate the loading process.
  • Automated overmolding (press to press transfer).
  • Automated assembly lines.
  • Automated stacking and sorting.
  • Automated inspection.
  • Automation of support processes.

Articulated Robot Advantages and Disadvantages

Articulated Robot Advantages

6-axis articulated robots are easy to align to different planes, are straightforward to control and manage, and can be quickly redeployed for plastic injection molding automation on a variety of types and sizes of injection molding machines, as well as for a variety of upstream and downstream applications.

The singularity phenomenon happens as the joints of the robot match up. With upright, slope, wall, or inverted mounting options, installation is incredibly versatile. It has integrated networking features, with Ethernet and serial links as standard. The reusability of such robots is another argument to turn.

Articulated Robot Disadvantages

The speed of these robots is one of their disadvantages. They are not as effective as other kinds of robots that can perform tasks at a high rate. Because of their various joints and degrees of freedom, this robots require complex kinematics to control their motion. They also have a higher component density, which creates an inertial barrier that must be resolved with any direction transition. If speed is an essential consideration in a factory’s cost-benefit study, so this type of robots may not be the best option.

Selective Compliance Articulated Robot Arm | SCARA Robot

A SCARA robot (full form is “Selective Compliance Assembly Robot Arm” or “Selective Compliance Articulated Robot Arm”) is an industrial robot. It’s arm is partially compliant in the X-Y direction but fix in the ‘Z’ direction due to the SCARA’s parallel-axis joint configuration, hence the term: Selective Compliant is applied here.

Compliance in robotics refers to a robot’s ability to move one or more joints. A compliant robot can yield to your touch if you press it. It isn’t going to fight back or stay there. SCARAs are flexible in the X-Y direction but stiff in the Z. This allows them more stability, which is especially helpful for assembly tasks that need obedience, such as putting a peg in a hole.

The SCARA’s second feature is its jointed two-link arm structure, which is identical to our human bodies. Thus the word “articulated.” This function allows the arm to stretch into tight spaces before retracting or “folding up” and out of the way. This is useful for moving pieces from one cell to another or loading and unloading enclosed process stations.

KUKA KR10 SCARA Robot; Image Source: Jo Teichmann, KUKA Industrial Robot KR10 SCARA

SCARA robots are often used in assembly procedures where small robots are used. Compliance is achieved by using a single plane with two parallel joints. This selective conformity ensures that although it is rigid along the Z-axis, it is flexible along the X-Y axes. Due to their atypical nature, SCARA robots can perform a wide range of material handling tasks.

SCARA Configuration; Image Source: Nikola SmolenskiSCARA configurationCC BY-SA 3.0

A SCARA robot’s construction is made up of the junction of two robotic arms, which are connected at the middle. Two autonomous motors power the X-Y movements of a SCARA robot. These motors employ interpolation and inverse kinematics techniques to guide the automated actions around these axes.

SCARA vs. Articulated Robot

As labor costs escalate and competition from low-wage overseas locations intensifies, the need for automation and robotics grows more extraordinary by the day. Simultaneously, product lifecycles are shortening, and the demand for customization and, as a result, component complexity is increasing. The best way to ensure manufacturing productivity and sound quality are to use flexible, regulated automation. The assembly process is now quicker, more effective, and more accurate than it has ever been, thanks to advances in automation in general and robotics in particular.

The 4-axis SCARA robot arm could shift X-Y-Z co-ordinate inside its work-envelope, is currently the most common robotics solution for assembly. The wrist rotation serves as a fourth axis of motion and 3- parallel-axis rotary joints include the X, Y, and roll motions. At the wrist or in the foundation, the vertical Z motion is usually a separate linear axis.

SCARA robots are usually employed in two dimentional assembly operations where the final step is a single upright motion to attach the component actually. Inserting components onto printed circuit boards is one example othher than this they are extensively utilized for pick-and-place,packaging works, and assembly installations.

When workpieces enter the robot cell at an angle, something must be done with SCARAs to make the part smooth, these proportione to more money and more machinery. One can use the robot to pick up and re-orient the component due to the vertically articulated robot’s dexterity. 5 and 6 axis articulating robotics are also adaptable to project modifications and provide more excellent stability before and after a program.

About Esha Chakraborty

I have a background in Aerospace Engineering, currently working towards the application of Robotics in the Defense and the Space Science Industry. I am a continuous learner and my passion for creative arts keeps me inclined towards designing novel engineering concepts.
With robots substituting almost all human actions in the future, I like to bring to my readers the foundational aspects of the subject in an easy yet informative manner. I also like to keep updated with the advancements in the aerospace industry simultaneously.

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